Re: [PATCH 16/23] arm64: ilp32: introduce binfmt_ilp32.c

[Zhangjian (Bamvor)]

Hi, Yury

On 2016/5/24 8:04, Yury Norov wrote:
> to handle ILP32 binaries
>
> Signed-off-by: Yury Norov <ynorov@xxxxxxxxxxxxxxxxxx>
> ---
>   arch/arm64/kernel/Makefile       |  1 +
>   arch/arm64/kernel/binfmt_ilp32.c | 91 ++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 92 insertions(+)
>   create mode 100644 arch/arm64/kernel/binfmt_ilp32.c
>
> diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
> index 6bc9738..9dfdf86 100644
> --- a/arch/arm64/kernel/Makefile
> +++ b/arch/arm64/kernel/Makefile
> @@ -28,6 +28,7 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE
>   arm64-obj-$(CONFIG_AARCH32_EL0)		+= sys32.o kuser32.o signal32.o 	\
>   					   sys_compat.o entry32.o		\
>   					   ../../arm/kernel/opcodes.o binfmt_elf32.o
> +arm64-obj-$(CONFIG_ARM64_ILP32)		+= binfmt_ilp32.o
>   arm64-obj-$(CONFIG_FUNCTION_TRACER)	+= ftrace.o entry-ftrace.o
>   arm64-obj-$(CONFIG_MODULES)		+= arm64ksyms.o module.o
>   arm64-obj-$(CONFIG_ARM64_MODULE_PLTS)	+= module-plts.o
> diff --git a/arch/arm64/kernel/binfmt_ilp32.c b/arch/arm64/kernel/binfmt_ilp32.c
> new file mode 100644
> index 0000000..a934fd4
> --- /dev/null
> +++ b/arch/arm64/kernel/binfmt_ilp32.c
> @@ -0,0 +1,91 @@
> +/*
> + * Support for ILP32 Linux/aarch64 ELF binaries.
> + */
> +
> +#include <linux/elfcore-compat.h>
> +#include <linux/time.h>
> +
> +#undef	ELF_CLASS
> +#define ELF_CLASS	ELFCLASS32
> +
> +#undef	elfhdr
> +#undef	elf_phdr
> +#undef	elf_shdr
> +#undef	elf_note
> +#undef	elf_addr_t
> +#define elfhdr		elf32_hdr
> +#define elf_phdr	elf32_phdr
> +#define elf_shdr	elf32_shdr
> +#define elf_note	elf32_note
> +#define elf_addr_t	Elf32_Addr
> +
> +/*
> + * Some data types as stored in coredump.
> + */
> +#define user_long_t		compat_long_t
> +#define user_siginfo_t		compat_siginfo_t
> +#define copy_siginfo_to_user	copy_siginfo_to_user32
> +
> +/*
> + * The machine-dependent core note format types are defined in elfcore-compat.h,
> + * which requires asm/elf.h to define compat_elf_gregset_t et al.
> + */
> +#define elf_prstatus	compat_elf_prstatus
> +#define elf_prpsinfo	compat_elf_prpsinfo
> +
> +/*
> + * Compat version of cputime_to_compat_timeval, perhaps this
> + * should be an inline in <linux/compat.h>.
> + */
> +static void cputime_to_compat_timeval(const cputime_t cputime,
> +				      struct compat_timeval *value)
> +{
> +	struct timeval tv;
> +	cputime_to_timeval(cputime, &tv);
> +	value->tv_sec = tv.tv_sec;
> +	value->tv_usec = tv.tv_usec;
> +}
> +
> +#undef cputime_to_timeval
> +#define cputime_to_timeval cputime_to_compat_timeval
> +
> +/* AARCH64 ILP32 EABI. */
> +#undef elf_check_arch
> +#define elf_check_arch(x)		(((x)->e_machine == EM_AARCH64)	\
> +					&& (x)->e_ident[EI_CLASS] == ELFCLASS32)
> +
> +#undef SET_PERSONALITY
> +#define SET_PERSONALITY(ex)						\
> +do {									\
> +	set_thread_flag(TIF_32BIT_AARCH64);				\
> +	clear_thread_flag(TIF_32BIT);					\
> +} while (0)
> +
> +#undef ARCH_DLINFO
> +#define ARCH_DLINFO							\
> +do {									\
> +	NEW_AUX_ENT(AT_SYSINFO_EHDR,					\
> +		    (elf_addr_t)(long)current->mm->context.vdso);	\
> +} while (0)
> +
> +#ifdef __AARCH64EB__
> +#define COMPAT_ELF_PLATFORM		("aarch64_be:ilp32")
> +#else
> +#define COMPAT_ELF_PLATFORM		("aarch64:ilp32")
> +#endif
fs/binfmt_elf.c use ELF_PLATFORM instead of the COMPAT one. Should we define
ELF_PLATFORM directly?
#undef ELF_PLATFORM
#ifdef __AARCH64EB__
#define ELF_PLATFORM            ("aarch64_be:ilp32")
#else
#define ELF_PLATFORM            ("aarch64:ilp32")
#endif

Regards

Bamvor
> +
> +#undef ELF_HWCAP
> +#undef ELF_HWCAP2
> +#define ELF_HWCAP			((u32) elf_hwcap)
> +#define ELF_HWCAP2			((u32) (elf_hwcap >> 32))
> +
> +/*
> + * Rename a few of the symbols that binfmt_elf.c will define.
> + * These are all local so the names don't really matter, but it
> + * might make some debugging less confusing not to duplicate them.
> + */
> +#define elf_format		compat_elf_format
> +#define init_elf_binfmt		init_compat_elf_binfmt
> +#define exit_elf_binfmt		exit_compat_elf_binfmt
> +
> +#include "../../../fs/binfmt_elf.c"